In general, rotary power tools are light-weight, handheld power tools capable of being equipped with a variety of accessory tools and attachments, such as cutting blades, sanding discs, grinding tools, and many others. These types of tools typically include a generally cylindrically-shaped main body that serves as an enclosure for an electric motor as well as a hand grip for the tool. The electric motor drives an output shaft to rotate at high speeds. The output shaft is equipped with an accessory attachment system that enables various accessory tools to be releasably secured to the power tool.
Accessory attachment systems for rotary power tools typically include a collet configured to grip the shank of an accessory tool. When attached to the rotary tool, the collet holds the shank of the accessory tool in line with the axis of the output shaft so the accessory tool can be driven to rotate about the axis by the motor. As the output shaft is rotated, an accessory tool is driven to perform a particular function, such as sanding, grinding, or cutting, depending on the configuration of the accessory tool.
The collet is usually attached to the output shaft of the motor of the rotary tool by a retention mechanism, such as a collet nut or collet chuck. A collet nut is installed over the collet and threaded into the end of the output shaft. The collet nut has a tapered bore so that as the collet nut is threaded onto the output shaft, the interior surfaces of the collet nut press the collet against the shank of the accessory tool thus securing the collet and accessory tool to the output shaft of the motor. While this method is effective for securing accessory tools to the rotary power tool, threading the collet nut onto and off of the output shaft of the motor can be time consuming and inconvenient and may require the use of separate tools for turning the collet nut.
As an alternative to threadedly attaching a collet to the output shaft, some previously known systems have been equipped with quick change mechanisms that enable accessory tools to be installed and removed from the collet without having to thread a collet nut onto and off of the output shaft. Quick change mechanisms typically include a collet chuck that is configured to hold the collet and have a mechanism for clamping down on the collet to cause the collet to grip onto the shank of an accessory tool. The clamping mechanism is manipulated by ribbed sleeve that can be grasped by the user. The ribbed cylinder, however, can be difficult for a user to hold onto and does not readily provide a visual indication as to the state of the clamping force applied to the collet.
In some quick change mechanisms, the collet is provided as a separate, removable component. Numerous factors must be taken into consideration in utilizing a removable collet. For example, the collet should be retained within the collet chuck while the tool is being operated and while the shank of an accessory tool is being inserted into and removed from the collet. The removable collet should also be capable of adequately gripping the shank of an accessory tool during use. In addition, care must be taken to ensure that the collet is oriented properly within the collet chuck so that the clamping mechanism can work properly.
There is a need for a rotary tool system having a quick change assembly that enables accessory tools to be easily installed and removed from the collet of the rotary tool and that can be easily accessed and manipulated by a user of the tool. There is also a need for a quick change assembly for a rotary tool that has a removable collet with enhanced gripping capability. In addition, there is a need for a quick change assembly that enables a removable collet to be releasably retained and/or properly oriented within the quick change mechanism without requiring an expensive or complex mechanism.